Electrically heated sauna unit



' Sept. 29, 1970 NMEER. 3,531,623

ELECTRICALLY HEATED SAUNA UNIT Filed March'13, 1967 2 Sheets-Sheet 1 I N VEN TOR. 44/20 //2-/ /a/ 755 Sept. 29, 1970 N. H. TEERI 3,531,623

ELECTRICALLY HEATED SAUNA UNIT Filed March 15, 1967 2 Sheets-Sheet 2 'INVENTOR.

A4740 flf/kle/ke/ BY A United States Patent US. Cl. 219-367 3 Claims ABSTRACT OF THE DISCLOSURE An electrically heated sauna oven having spaced inner and outer mantles to permit air circulation from the bottom to the top of the oven through the space between the mantles. A stone-receiving container has a portion thereof extending into the upper end of the inner mantle. A first group of resistance elements encircles that portion of the stone-receiving container extending into the inner mantle. A second group of resistance elements is disposed below the container. The first and second groups of resistance elements are operable independently of one another. The resistance elements are connected to a power source and are operable to heat the circulating air passing thereover to thereby heat the air entering the bath house (sauna) and the stone pile in the container. The resistance elements also contribute to the heating of the stones.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to electrically heated sauna units. More particularly, the invention relates to thermostatically controlled electrically heated sauna units in which the air and stones are efliciently heated.

Description of the prior art rificing too much as concerns the amount and depth of stone pile.

SUMMARY OF THE INVENTION It is towards these objectives that this invention is directed, and more particularly to provide an efiicient, thermostatically controlled electrically heated sauna unit in which the stove unit therefor is equipped with a system of mantles permitting air to circulate upwardly therethrough, said air being heated While flowing over resistance coils connected to a power source, thereby heating the air entering the bath house (sauna) and the stone pile contained in said stove unit, said resistance coils also contributing to the heating of the stones. The heating elements (resistance coils) are arranged in two groups, upper and lower. The upper group encircles the container holding the stones, whose upper end is open and whose lower end is provided with a grate, while the lower group is positioned below the said grate. The entire arrangement results in the eflicient heating of the air entering the sauna and the stone pile.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 presents a vertical section of the stove from the side taken along line 1-1 in FIG. 2.

3,531,623 Patented Sept. 29, 1970 FIG. 2 presents one half of the stove from above taken along line A in FIG. 1 in the direction of the arrow adjacent the reference letter.

FIG. 3 presents the other half of the stove from above taken along the line BB in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention refers to an electrically heated sauna unit having a system of mantles which permits air to circulate through the stove from the bottom upwardly, and to be heated by passing over resistances. Thus, heating the bath house air and contributing also to the heating of the stone pile, as part of the hot air circulates through to the stones. The stones are also partly subjected to direct or indirect heat radiation from the resistances arranged in two groups which is the characteristic feature of the invention. The heating elements are arranged in two groups in a manner such that the upper resistance, or group of resistances, is wound around the upright stone space having a cylindrical or other shape and made of steel or other suitable material with the upper end open and the lower end provided with a grate which is partly open or closed, this permits the mantle surface of the aforementioned stone space to be made glowing hot such that the heat transmission to the stones is efiiciently maintained while there is less heating of the circulating air passing directly to the bath house. The lower resistance or group of resistances is situated below the stones in a manner that the air circulating in the stove is able to efiiciently sweep over said resistances from all sides. The main part of the heat from these resistances is transferred to the hot room air by mainly heating the circulating air passing directly into the sauna which also contributes to the heating of the stones. This produces the coupling of the heat resistances thus situated, therefore, when the electric power is switched on, all the heat resistances, the sauna and the stones in the stove are effectively heated. However, when the sauna has reached the desired temperature a regulator ceases current conduction through the lowest resistance or resistances, so that the heat transmission to the hot room air is considerably reduced, whereas the eflicient heat transmission to the stones is continued due to the upper heat resistances surrounding the stones.

The basic parts of the stove are: the stone space 1, the upper heat resistances 6, the lower heat resistances 7, and the coupling box 8. In FIG. 1 the path of the circulating air is presented by thin arrows.

When the stove is installed and the electric lines are brought through the connecting sleeve 9 into the coupling box 8, where they are switched in the desired manner to the heat resistances 6 and 7, the stove is ready to operate. When operating at full power all the heat resistances 6 and 7 are glowing hot. The heat resistances 6 are so situated, that they surround the cylindrical mantle 1a of the lower part of the stone space 1 making this glow while heat is transferred efficiently to the stones. The heat resistances 7 are situated below the stone space and are shaped in such a way, that the air moving inside of the inner mantle 2 due to the draft comes in best possible contact with these resistances, whereby the circulating air is effectively heated and the main portion of the air passes into the sauna through the opening 10 at the upper part of the stove, while part of the hot air passes through the stone space 1 and contributes to the heating of the stones. At the bottom, the stone space 1 is provided with a grate 12 supporting the stones. The circulating air also transfers heat to the sauna air from the surface of the heat resistances 6, though a comparatively large part of the heat of these resistances is transferred only to the stones.

When the air in the sauna is sufiiciently warmed up, for instance to 90 C., the current is cut off from all the lower resistances 7, or for instance from the three lowest ones. This is usually carried out by thermostat control. Because only the upper resistances 6 and possibly the uppermost of the resistances 7 now are glowing, the air circulation inside of the inner mantle 2 is considerably less pronounced than a while ago on account of the smaller draft, which is due to less heat developed Within the inner mantle 2, but before all due to the fact that the distance in height travelled by the air in hot state is smaller. Thus the surface temperature of the upper heat resistances still remains high and the resistances 6 deliver their heat effectively to the stones. In order for the air circulating through the stone pile to be as hot as possible, the walls of the stone space 1 are provided with holes 13, which interfere with the development of draft in the stone space and retard the air circulation therein. In this way the temperature of the stone pile is kept high, despite the reduced total effect of the stove and plenty of water thrown to produce steam.

The stone space 1 is further provided with air circulation holes 14, the main purpose of which is to conduct hot circulation air to heat the stones located at the edges of the wider upper end of the stone space, especially when all the resistances are glowing.

The chief purpose of the bottom of the stove is to prevent direct heat radiation on the foundation plate on the floor below the stove. The air flowing between the mantles 2 and 3 of the stove prevents harmful heating of the outer mantle of the stove, so that the heat radiating from the stove is not felt too much and the surface of the outer mantle is not dangerously burning hot. This circulating air also cools down the connecting ends 6a and 7a of the heat resistances 6 and 7 before they enter into the coupling box 8. This prevents oxidation of the connecting points which has proven to be harmful in electric stoves.

A characteristic feature of the stove according to the invention is also the deep stone pile, due to which plenty of steam producing water does not flow all the way through the stones but has time to give off steam and offer a proper sauna bath.

The invention is not restricted alone to the working example described above and illustrated in the drawings, but it can be applied in different forms, for instance, de-

pending upon desired outer appearance.

What is claimed is: 1. An electrically heated sauna oven comprising an air circulation mantle, in turn comprising an inner and an outer mantle, said inner mantle having an air inlet means at its lower end and an air outlet means at its upper end, said outer mantle surrounding said inner mantle and being spaced therefrom and including air inlet means to and air outlet means from said space between said inner and outermantles to permit the passage of circulating air therethrough, a stone-receiving container mounted to the upper part of said air circulation mantle and having at least a portion thereof extending into the upper end of said inner mantle, and a plurality of resistance elements comprising two vertically spaced groups of resistance elements, including an upper group encircling at least a part of the portion of said stone-receiving container extending into said inner mantle for direct heating thereof and a lower group disposed below said container, said lower group being capable of independent operation from said upper group and further comprises several resistance elements winding in horizontal planes above one another and covering substantially the entire horizontal cross section of said inner mantle, said stone-receiving container being provided with a gate at the bottom thereof for supporting oven stones, said stones being loosely spaced upon said grate forming air circulation spaces therebetween, so that part of the circulating air heated by said lower group of resistance elements is able to pass through said grate into said stone spaces, opening means being situated in said stone-receiving container where said stones are located for permitting a part of the circulating air heated by said lower group of said resistance elements to also pass through said opening means into said stone-receiving container. 7

2. A sauna oven as in claim 1, wherein the resistance elements are coupled in such a manner, that they can be operated at partial power, at which the upper group is heating mainly the oven stones, while the lower group is cooling off thereby decreasing the air circulation in said oven.

3. A sauna oven as in claim 1, wherein said opening means comprise a plurality of apertures located respectively at the upper and lower ends of said stone-receiving container.

References Cited UNITED STATES PATENTS 2,654,018 9/1953 Sandberg 219-378 3,147,367 9/ 1964 Magnusson. 3,277,274 10/1966 Raabe 219-362 3,337,715 8/1967 Finn 219367 3,348,021 10/1967 Skogland et al. 219370 3,400,248 9/1968 Isomaa 219-365 X FOREIGN PATENTS 256,963 3/ 1949 Switzerland.

ANTHONY BARTIS, Primary Examiner US. Cl. X.R. 219-365, 378 

